Brush structure



Nov. 10, 1964 K. v. HARDMAN ETAL BRUSH STRUCTURE 2 Sheets-Sheet 1 Filed Feb. 2, 1960 INVENTOR-S KENNETH V HARDMAN ARTHUR J'. LANG ATTORNEYS Nov. 10, 1964 K. v. HARDMAN ETAL 3,155,993

BRUSH STRUCTURE Filed Feb. 2, 1960 2 Sheets-Sheet 2 FIG 4 FIG. 5

INVENTORS KENNETH V. HARDMAN ARTHUR J. LANG- United States Patent C 3,1553% BRUSH STRUCTURE Kenneth V. ltlardman, Upper Montclair, and Arthur 3. Lang, Cedar Grove, N..li., assignors to H. V. Hardman Company, inc, a corporation of New .lersey Filed Feb. 2, was, Ser. No. 6,244 8 Claims. (Cl. i--192) Paint brushes that include a metal ferrule and hollow plastic handle are known and are being sold in commerce toda In the manufacture of these brushes great difficulty has been experienced in anchoring the hollow plastic handle in the metal ferrule of the brush. Existing commercial machines for nailing a wooden handle in place in the metal ferrule can not be employed because the skirt at the bottom of the hollow plastic handle collapses under the force of the blow used to drive the nails home.

Suggestions have been made to insert a wood block in in the skirt of the hollow plastic handle to reinforce the skirt so that it will withstand the force of the nailing blows without collapsing. While the hollow plastic harp dle reinforced with a wood block provides a satisfactory commercial product it is still necessary to use nails for anchoring the plastic handle in place in the metal ferrule. The brush with plastic handle is competitive withordinary brushes having a conventional wood handle but in both structures there is a tendency for the nails to loosen and pull out of the wood which materially shortens the useful life of the brush. Another problem experienced with wood handles is that during assembly the nails frequently split the wood and when this occurs the brush must be discarded.

In accordance with the present invention it is now possible for the first time to secure a hollow plastic handle in place in a metal ferrule without using nails or other fasteners. This is done by means of a hollow plastic handle which includes a skirt at the bottom end portion there of which is so dimensioned as to provide a small clearance between the metal ferrule and at least two of the side walls of the molded skirt of the handle.

The method of assembling the brush is new. The brusl is assembled by securing a bristle knot in the metal ferrule in conventional manner and thereafter a pool of liquid cement adapted to set at ordinary atmospheric temperature and pressure is poured into the metal ferrule on top of the bristle knot. Then while the cement is still in liquid form the skirt of the hollow plastic handle is pushed down into the metal ferrule until the lower end portion of the skirt is submerged in the pool of liquid cement.

It is important in the structure of the present invention to provide a small clearance between the metal ferrule and at least two of the side walls of the skirt of the handle so that liquid cement can flow upwardly into the small clearance between the exterior surface of the wall of the skirt and interior surface of the wall of the ferrule. When this is done the bonding action of the cement is extended upwardly over a substantial portion of the wall of the skirt above the level of the pool of liquid cement in the ferrule. The clearance between the skirt of the hollow plastic handle and metal ferrule is of the order of size such as would provide capillary attraction between the liquid cement and solid walls of the plastic skirt and metal fer rule and whether it is capillary action or the escape of compressed air from the interior of the ferrule which causes the liquid cement to flow upwarldy into the space between the two walls we do not now know. The fact remains, however, that the liquid cement is distributed over a substantial area of the exterior wall of the skirt above the level of the pool of liquid cement and it is the bonding in this area which securely anchors the hollow plastic handle in the metal ferrule without using nails or 3,155,998 Patented Nov. 10, 1954 ice other metallic fasteners. An additional anchor for'the handle is achieved by means of a plurality of holes posi tioned in the bottom end portion of the skirt of the bandle. The bottom rim of each hole is submerged in the pool of liquid cement and the submerged portion of the rim of the holes in the hardened cement assists in anchoring the hollow plastic handle in the metal ferrule by me chanical means.

The adhesive is an important and critical element in the structure of the present invention and only those adhesive cements such as the epoxy resins which set at ordinary atmospheric temperatures and pressures are of practical commercial value. Heat setting adhesives which require temperatures ranging up to 45 0 F. are inoperable because the thin hollow plastic handle tends to soften and distort at such elevated temperatures.

Further details and advantages of the structure of the present invention may be readily understood by reference to the accompanying drawings in which FIG. 1 is a side view of a preferred form of hollow plastic handle of the present invention prior to assembly in the ferrule of the brush.

FIG. 2 is a side view of the brush of FIG. 1 after the hollow plastic handle is assembled in the structure of the brush.

FIG. 3 is a sectional view taken on line 3-3 of FIG. 2.

FIG. 4 illustrates another form of the handle of PEG. 1.

FEG. 5 illustrates a modified form of the handle of FIG. 1.

As best shown in FIG. 1 the brush of the present invention includes an ordinary metal ferrule 1d having bristles 12 secured in the bottom of the ferrule in conventional manner well known in .the tart. synthetic or natural and any type of adhesive including those which are set by heat may be employed for anchoring the bristle knot 14 in the metal ferrule. If a heat hardenable cement is employed for setting the bristles the cernert is cured before assembling the handle in the metal ferrule. While a metal ferrule is preferred this is not necessary and the ferrule may be made of any suitable material including synthetic plastic materials.

The top of the bristle knot is preferably positioned below the conventional annular head 15 of the ferrule so that the pool of liquid cement 18 (later described) will fill the head which thereby assists in locking the block of adhesive in place in the metal ferrule. But this is not necessary and the top of the bristle knot may extend above bead 16.

Best results and the most economical assembly is achieved by using the same cement for bonding the bristle knot and the hollow plastic handle in the metal ferrule. This cuts down on the number of operations required for assembling the brush and it provides a single block of cement that unites the bristles and hollow plastic handle into a unitary structure having great strength and rigidity. In such case the bristle knot is assembled in the metal ferrule in conventional manner and then a cement which is self curing at atmospheric temperature and pressure is poured in on top of the bristle knot in conventional manner and in accordance with the present invention pouring is continued until a pool 13 of liquid cement is formed on top of the bristle knot. Consistency of the liquid cement is controlled in the usual manner to provide the desired penetration of cement down into the knot of the bristles. if desired pouring may the carried out in two steps. In such case the liquid cement which bonds the bristle knot is first poured into the ferrule and cured at atmospheric temperature and pressure to the point where it will support the bristles so that they may be trimmed in the usual manner. Thereafter the .pool of liquid cement 18 may be poured into the ferrule on top of the bristle knot as a separate second step.

While pool 18 is still in liquid state the hollow plastic The bristles may be either handle is inserted into the metal ferrule. As shown in the drawings hollow plastic handle 20 is provided with an elongated skirt 22 in the form of a continuous sleeve which has a plurality of holes 24 positioned in the bottom end portion thereof. For the purpose of the present invention best results are achieved with holes having an opening of about of an inch in its largest dimension. The sleeve of skirt 22 of the handle is so dimensioned that there is a small clearance 26 between the wall of the metal ferrule 10 and the four walls of the skirt. The small clearance 26 shown in the drawings is not to scale but is enlarged for the purpose of illustration. The clearance between the skirt of the handle and wall of the metal ferrule on any one side or" the brush is not more than about of an inch and since the space is of the order of magnitude which provides capillary action the term capillary space is used to identify the small clearance. The hollow plastic handles are molded by conventional means and there is no difiiculty in maintaining the desired tolerance between the handle and wall of the ferrule to establish the capillary space as this is within ordinary commercial tolerances for molded plastic items. Such tolerances could not be maintained as a practical matter with wood handles which lack the dimensional stability of molded plastic items.

The brush assembly is completed by inserting the skirt of the hollow plastic handle in the metal ferrule and by pushing it down until at least the rim at the bottom of holes 24 is submerged in the liquid. The holes may be completely submerged in the pool of liquid cement as shown in the drawings. When the skirt is pushed down into the metal ferrule the air in the ferrule is compressed but the air is free to escape through the capillary space between the skirt and handle until the bottom of the skirt establishes a seal with the liquid cement. Thereafter capillary action or the compressed air or both cause the liquid cement to flow upwardly into the capillary space throughout a substantial area above the level of the top of the holes 24. The liquid cement in the capillary space provides rigid upright flanges that seal off the hollow of the handle and materially assist in anchoring the skirt of the handle to the block of cement formed by the pool when hard. In some cases there may be a tendency for the liquid cement to flow out over the rim at the top of the ferrule. If this occurs a small vent hole 25M may be molded into the top of the handle in order to vent the hollow of the handle to the atoms phere. In such case capillary attraction is primarily responsible for causing the liquid cement to flow upwardly into the capillary space as described hereinabove. After the handle 20 is positioned in the ferrule the assembly may be set aside at room temperature until the pool f liquid cement has hardened into a rigid block which locks the handle in place in the ferrule by adhesive as well as mechanical means. The hardened cement fills the capillary space in the area above the top of holes 24 and this is of advantage since the cement forms a seal between the plastic handle and metal ferrule which prevent water, paint and other solvents from seeping into the interior of the brush especially in those cases Where only a portion of each hole is submerged in the cement.

In some cases as in automatic and conveyorized assem bly it may be desirable to accelerate the cure of the liquid cement by means of heat. For example the pool of liquid epoxy cement in a brush assembly made with thin wall hollow polyethylene handle was cured and set by placing the brush assembly in a hot air oven held at 190 F. for a period of thirty minutes. At the end of this time the pool of epoxy resin had been set and hardened and there was no sign of deformation of the handle.

In pilot plant work infrared radiation was found to be particularly effective for heating the brush assembly as this quickly accelerated the cure of the liquid cement and there was no deformation of the thin plastic wall of the handle. In the use of infrared radiation care is 4 taken to be sure that the temperature does not exceed that temperature at which deformation of the handle would occur during cure.

Conventional sources for generating infrared radiation such as infrared lamps or wire coils which generate infrared radiation may be employed. If wire coils are used they are positioned in conventional manner in a hood which has a reflective surface to provide even distribution of heat (not shown). The brushes may be passed through the hood by means of a conventional type conveyor. Accelerating the cure of the cement greatly expedites packaging problems and the brushes may be manufactured and shipped in one continuous operation without waiting for the cement to cure at atmospheric temperature and pressure.

As to the liquid cement only those liquid cements which are adapted to cure at atmospheric temperature and pressure may be employed in the structure of the present invention and cements which require heat treatment to effect cure at temperatures above the softening point of the plastic material of the handle are inoperable since the handle would be deformed during the curing operation. For example in the case of a polyethylene hollow handle deformation will take place at a temperature of about 265 F. Polypropylene handles will deform at a temperature of about 345 F. and nylon handles will dcform at a temperature of about 450 F. Softening temperatures of the other known plastic materials are reported in the literature. As used in the specification and claims the operable cements which are adapted to be cured at atmospheric temperature and pressure are identified as self curing liquid resinous cements. in this connection it will be understood that the heat treatment specified above is used merely to accelerate the cure of the liquid cements which are adapted to cure at atmospheric temperature and pressure.

Some examples of suitable liquid cements which are self curing at atmospheric temperature which have been employed with excellent results include cold setting resorcinol resins which may be identified as a resorcin formaldehyde resin having insufficient aldehyde groups to cause the resin to set to an infusible insoluble state. The resin includes a suitable catalyst and it is made to set at room temperature by adding a curing agent containing either active methylene radicals or active methylol radicals such as are present in a 37% solution of formaldehyde. Such cold setting resorcin liquid cement is sold by the Koppers Company under the trade name Penacolite GU24 and Gl13l. The catalyzed resorcin formaldehyde resin and curing agent are mixed and then the mixture is poured into the ferrule as described hereinbefore.

Low pressure laminating polyester resins may also be employed as the liquid cement in the structure of the present invention.

Polyester resins are readily available on the open market and the ones which are suitable for use in the man ufacture of our brushes are known in the art as low pressure polyester laminating resins. These are characterized by the fact that they may be cured at room temperature and at ordinary atmospheric pressure. These polyester resins are further characterized by the presence of unsaturated carbon bonds which undergo polymerization during cure without liberation of water. The resins are made of three groups of compounds acids, such as maleic, furnaric, itaconic and phthalic; alcohols or glycols, such as allyl alcohol, ethylene glycol and diethylene glycol and unsaturated hydrocarbons such as styrene, cyclopentadiene and other similar compounds. The polyester resin is prepared by condensation of the acid and alcohol and it must contain at least one unsaturated compound. This may be either an unsaturated alcohol or acid. The resulting unsaturated polyester resin is then capable of polymerizing upon cure to form cross linked three dimensional structures. The polyester resin is mixed with an unsaturated hydrocarbon liquid such as styrene which acts as a solvent vehicle for the resin and upon the addition of a suitable peroxide catalyst, such as MEK peroxide or benzoylperoxide with cobalt naphthanate as an activator, the resin is made to cure at ordinary room temperature and pressure.

For our purpose the polyester resin is thinned with styrene until itis fluid enough to give the desired penetration down intotthe bristle knot. Ordinarily parts of styrene are used for 100 parts of the polyester resin. It will be understood that any of the liquidpolyester resins which set at ordinary room' temperature and pressure may be used in" the manufacture of our brushes. These polyester resins are sold on the open market under the trade names of Laminac, Paraplex and 'Vibrin.

Best results are achieved by means of epoxy resinous condensation products that cure at atmospheric temperature and pressure. These epoxy adhesives may be identified as the products of condensationof epicholorohydrin with hydroxy aryl compounds or ethylene glycol, glycerol or related .aliphatic compounds. Epoxy-resins mayfor example be formed by reacting together in known manner bisphenol-A with an epoxy compound such as epicholorohydrin and the resulting liquid condensation product is cured at room temperature with'an amine such as diethylene triamine. Epoxy resins are sold on the open market under the trade names Epon and Araldite. The resin itself may be used or it may be compounded in conventional manner with the usual ingredients to improve adhesion and control penetration into the bristle knot.

Referring to FIG. 2, the bottom of skirt 22 of the handle is positioned in spaced relationship to the top of the bristle knot but if desired the bottom edge of the skirt may just make contact with the top of the bnistle knot. In those cases where the skirt of the handle is inserted into the pool of liquid cement in the ferrule before the cement of the bristle knot has completely hardened and set care must be taken to avoid applying any substantial pressure against the top of the bristle knot such as would dislodge the bristles from position in the metal ferrule. In the preferred embodiment of the invention shown in the drawings we provide a shoulder 28 at the top of the skirt of the handle which is adapted to contact the top edge of the ferrule when the parts are assembled. The length of the skirt below shoulder 28 is so dimensioned that the bottom of the skirt will be positioned just above the bristle knot when shoulder 28 is in contact with the top edge of the metal ferrule. In this way there is no danger of dislodging the bristle knot when the hollow plastic handle is inserted into the ferrule. It will be understood that shoulder 23 is not essential as the same results may be achieved by careful insertion of the handle into the metal ferrule.

Since the hollow plastic handle is most economically produced with thin walls, the skirt of the handle in the larger size brushes may not have the desired rigidity. In such cases reinforcing ribs 30 which extend across between the opposite side walls of the handle may be employed to give the skirt the desired rigidity. If ribs 30 are used they may also be provided with a plurality of holes across the bottom end portion thereof in order to increase mechanical locking action of the cement on the plastic handle.

Any of the known plastic materials may be employed in the manufacture of the hollow plastic handle. For example excellent results have been achieved with a hollow plastic handle made of nylon, polyethylene or polypropylene. Best results are achieved with a hollow polypropylene plastic handle and with epoxy resinous cements which are self curing at ordinary atmospheric temperature and pressure. While the hollow plastic handle shown in the drawings is preferred it will be understood that the handle may be of solid plastic provided, however, that there is an opening in the skirt adapted to receive liquid cement. A solid skirt without an opening for the liquid cement would not be useful as a practical matter because the pool of liquid cement would be subjected-to great pressure by the solid skirt either because of physical contact between the solid skirt and'liquid-or because of expansion of air causedby the heat generated by the self curing liquid resinous cement. As a resultthe pressure would either dislodge the bristle-knot or the cement would flow out at the top of the rim of the ferrule.

The hollow plastic handle 31'shown in FIG. 4 is of identical construction with that shown in PIG. 1 with the exception that the side wall of the skirt at opposite ends thereof does-notextend down to the bottom edge of the side walls of the skirt as it does in the structure of FIG. 1. The opposite end walls 32 are long enough to project down below the top edge of the metal ferrule for a distance of at least about one quarter of an inch to avoid any chance of a crack or space between the top edge of the ferrule and'bottom edge of the end walls 32 of the skirt. By cutting away a portion of the end walls of'the skirt the air in the metal ferrule is readilyvented to the atmosphere but the liquid cement flows up'into the capillary space to fill a substantial area of the space above the level of the holes of the skirt of the handle. In such case it is the capillary attraction which is primarily re. sponsible for causing the liquid cement to fill the capillary space. The structure of FIG. 4 has commercial utility but it does not have the advantage of the seal which closes off the hollow of the handle of FIG. 1 since the liquid cement only fills the capillary space between the ferrule and two opposite side walls of the skirt of the handle. The liquid cement does not fill the capillary space between the ferrule and the side walls 32 positioned at opposite ends of the skirt of the handle.

In FIG. 5 a modified form of the hollow plastic handle of FIG. 1 is shown. The plastic handle 34 of FIG. 5 is of identical construction with the one shown in FIG. 1

with the single exception that the bottom of the skirt of the handle is provided with a wall 36 which completely encloses the hollow of the skirt. In this case a plurality of holes 38 are positioned in wall 36 and when the brush is assembled the holes are submerged in the pool of liquid cement which flows upwardly through the holes to lock the handle in place by mechanical means. The forces causing the liquid cement to fill the capillary space between the skirt and ferrule are quite strong with this construction and care must be taken to avoid having the liquid cement flow out at the top of the metal ferrule. For this reason the structure shown in FIG. 5 is not preferred but with proper control of the amount of liquid cement used in the pool the structure certainly has commercial utility. The handle of FIG. 5 may be manufactured by so-called blow molding processes which are well known in the art.

It will be understood that it is intended to cover all changes and modifications of the preferred embodiment of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. A paint brush comprising a ferrule, a plurality of bristles positioned in one end portion of said ferrule, a plastic handle having an open ended skirt portion which extends down into the ferrule, said skirt being dimensioned to provide a capillary space between the interior wall of the ferrule and the exterior of at least two opposite portions of the side wall of the skirt, a hardened block of self curing resinous cement which is positioned in the ferrule, on top of the said plurality of bristles and which has upright portions that extend into the capillary space throughout a substantial portion of the area of such space to seal off the interior of the hollow skirt and provide additional adhesive bonding between the skirt of the handle to assist in anchoring the plastic handle in the ferrule, the rim at the bottom of said open ended skirt being positioned in the hardened block of cement.

2. A structure as specified in claim 1 which includes a plurality of holes positioned in the skirt adjacent the bottom edge thereof, the bottom rim of said holes being submerged in the said block of cement to assist in anchoring the handle in the ferrule by mechanical means.

3. A structure as specified in claim 1 which includes a shoulder positioned in the side Wall of the brush at the top of the skirt, said shoulder being in position against the rim at the top of the ferrule.

4. A structure as specified in claim 1 in which the skirt of the plastic handle is provided with a reinforcing rib that extends across between opposite side Walls of the skirt.

5. A structure as specified in claim 1 in which the ferrule is provided with an annular bead in the side wall thereof which is filled with the solid cement.

6. A structure as specified in claim 1 in which the bottom edge of the skirt is in contact with the surface at the top of the plurality of bristles in the ferrule.

7. A structure as specified in claim 1 in which the skirt has a Wall of plastic material across the open end thereof 8 which is provided with a plurality of holes, said holes being submerged in the block of solid cement.

8. A structure as specified in claim 1 which includes a vent hole adapted to vent the hollow of the skirt of the handle to the atmosphere.

References Cited by the Examiner UNITED STATES PATENTS 1,915,057 6/33 Foss 15l93 2,310,186 2/43 Abrams 15-193 X 2,406,732 8/46 Hardman et a1. 300-21 2,562,716 7/51 Hervey 15-493 X 2,610,345 9/52 Simms l5192 X 2,854,684 10/58 Hardman et al 15-193 FOREIGN PATENTS 156,999 11/56 Sweden. 543,646 12/55 Belgium.

20 CHARLES A. WILLMUTH, Primary Examiner. 

1. A PAINT BRUSH COMPRISING A FERRULE, A PLURALITY OF BRISTLES POSITIONED IN ONE END PORTION OF SAID FERRULE, A PLASTIC HANDLE HAVING AN OPEN ENDED SKIRT PORTION WHICH EXTENDS DOWN INTO THE FERRULE, SAID SKIRT BEING DIMENSIONED TO PROVIDE A CAPILLARY SPACE BETWEEN THE INTERIOR WALL OF THE FERRULE AND THE EXTERIOR OF AT LEAST TWO OPPOSITE PORTIONS OF THE SIDE WALL OF THE SKIRT, A HARDENED BLOCK OF SELF CURING RESINOUS CEMENT WHICH IS POSITIONED IN THE FERRULE ON TOP OF THE SAID PLURALITY OF BRISTLES AND WHICH HAS UPRIGHT PORTIONS THAT EXTEND INTO THE CAPILLARY SPACE THROUGHOUT A SUBSTANTIAL PORTION OF THE AREA OF SUCH SPACE TO SEAL OFF THE INTERIOR OF THE HOLLOW SHIRT AND PORVIDE ADDITIONAL ADHESIVE BONDING BETWEEN THE SKIRT OF THE HANDLE TO ASSIST IN ANCHORING THE PLASTIC HANDLE IN THE FERRULE, THE RIM AT THE BOTTOM OF SAID OPEN ENDED SKIRT BEING POSITIONED IN THE HARDENED BLOCK OF CEMENT. 